bug(architect): generated L4 verification-property files diverge from canonical L4-verification-property-template

## Summary

In one external pilot run, all generated verification-property (VP) files produced by the architect agent did not conform to the engine's own canonical `templates/L4-verification-property-template.md`. The divergence was not minor: required frontmatter fields were absent across the entire generated set, and the lifecycle block structure was missing.

The defect was discovered mid-phase via a proactive `validate-template-compliance` / `conform-to-template` run. Without that intervention, a review loop would have excavated the conformance gaps one VP per pass — an estimated ~17 additional review pass-pairs to drain the full set.

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## What diverged

Required fields and structural elements defined in `templates/L4-verification-property-template.md` that were missing from the generated files:

**Frontmatter fields missing:** `source_bc`, `proof_method`, `level`, `producer`, `timestamp`, `inputs`, `input_hash`, `feasibility`, `verification_lock`, and method-specific `proof_*` fields.

**Body structure missing:** the lifecycle block.

All VP files generated in the pilot exhibited the same gap, indicating the VP-generating agent or the template path it follows is systematically out of sync with the shipped `templates/L4-verification-property-template.md`.

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## Distinction from existing issues

- **#277 / #310** — those address derived count totals and traceability tallies drifting after VP addition/deletion. This issue is about the body and frontmatter schema of generated VP files failing to match the canonical template at generation time.
- **#300** — that addresses the L1 artifact-path registry. This issue is about the content shape of generated L4 files, not their registered paths.

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## Recommended remediation

1. **Generation-time post-condition:** after any VP-authoring burst by the architect agent, run `validate-template-compliance` automatically. Block phase continuation if any generated VP file fails conformance.
2. **Pre-phase lint gate** (aligns with the companion pre-review-lint enhancement): every VP file must pass `validate-template-compliance` before the first adversarial pass of any phase.
3. **Architect template alignment audit:** audit the architect agent's internal VP template / generation prompt against the current `templates/L4-verification-property-template.md`. The systematic nature of the gap (all files missing the same fields) indicates the generation source, not the individual files, is the root cause.